In conventional cameras, 35 mm film cartridges or cassettes are loaded from the side through a hinged camera back into a loading chamber on one side of the image frame exposure gate, and the filmstrip is either manually or automatically directed through the exposure gate and wound on a take-up reel. After all image frames are exposed, the filmstrip is either automatically rewound by a motorized drive or manually rewound into the cartridge. The cartridge is then typically removed by opening the hinged camera back, releasing the drive from the cartridge spool hub and manually withdrawing the cartridge from the loading chamber.
More recently, it has been proposed to load and eject conventional 35 mm cartridges and "thrust" style film cartridges in an end-wise fashion through a sliding or pivoted door in the bottom, top or side of the camera body and to employ motorized filmstrip winding and rewinding apparatus to advance and rewind the filmstrip with respect to the cartridge. Such cameras are disclosed in various configurations, for example, in commonly assigned U.S. Pat. No. 5,049,914 and in U.S. Pat. Nos. 4,363,547, 5,105,211, 5,155,514, 5,159,365 and 5,142,316, and 5,231,438.
In the '914, and '438 patents, and in the above listed patent applications, a camera loading chamber and mechanism is provided for receiving a thrust style film cartridge which does not have a protruding film leader and has an actuable cartridge door through which the filmstrip is advanced and rewound when the door is opened. Referring now to the drawings and first to FIG. 1, it depicts in perspective view a thrust style film cartridge 10, as shown in the above-referenced '170 application, containing a filmstrip wound on and attached at one end to a spool (both obscured within the opaque plastic cartridge shell). The two ends of the spool hub 16 are exposed through light-tight, bearing openings in the free end 11 and seated end 12 of the cartridge 10, so that the spool and attached filmstrip may be rotated by rotation of the spool hub 16 upon seating of the cartridge 10 in a camera film loading chamber.
The film cartridge 10 is shaped to form an elongated snout or lip 14 having a filmstrip passage door 18 therein (depicted in a closed position). The door 18 fits in a door opening 24 and is attached to a rotatable door drive hub 26 that extends through openings in the free end 11 and seated end 12. The door 18 and rotatable door drive hub 26 are formed in one piece and comprise a light lock for the cartridge when fitted into the door opening 24 that replaces the passive, relatively tight, plush lined light lock employed for many years on 35 mm film cartridges. The free end of the filmstrip may be thrust out of the cartridge shell 12 through the door opening 24 by application of counter-clockwise rotary motion to the door drive hub 26 to open the door 18 and by the application of clockwise rotary motion to the spool hub 16 at the seated end 12 to thrust its leading end out past the open door 18.
A retention slot 20 is depicted formed in the inner surface of cartridge snout 14 extending longitudinally between portions 22 and 23 of respective ends of cartridge snout 14 and cartridge shell 12. The retention slot 20 may be employed for cooperation with a spring loaded retention member of the type described in the above referenced '969 patent and '170 application for preventing the cartridge 10 from falling out of or being forcibly ejected completely from the loading chamber 30 when it is deployed in the manner described therein. In particular, the slot 20 may be engaged by a retention member during movement of the film cartridge 10 from the camera loading chamber as proposed in certain of the above-referenced co-pending applications. Various improved apparatus and methods are disclosed therein for receiving and ejecting the cartridge from the loading chamber, wherein the retention slot 20 is engageable by various retention members upon partial insertion into the chamber and remains in engagement upon ejection to prevent the film cartridge 10 from falling out of the loading chamber. The user may typically complete the withdrawal of the cartridge 10 by simply pulling the partially ejected cartridge out, overcoming the retention force.
In certain of the above-listed patents and in all of the above-listed patent applications, the film cartridge loading chamber or holder is either deployable outward from the camera body, as shown for example in the '316, '547 and '211 patents, or is accessible through an end cover as shown in the '438 patent. Latch mechanisms are required for closing the end covers or securing the deployable chamber in the closed position. The '316 patent discloses a typical outward deployable cartridge holder for accepting a film cartridge. In one embodiment, the holder is pivotally supported by a shaft for movement between an outwardly deployed open position in which the holder projects transversely from the camera body and a closed position in which the cartridge holder stands vertically in the camera body. Upon movement into the closed position and with a film cartridge inserted, the upper end of the cartridge is engaged by a lever to hold the cartridge down. The cartridge holder is normally urged towards the open position. A locking lever operates to retain the cartridge holder in the closed position and is coupled with a knob exposed to the exterior of the camera body. A pin extending from the cartridge holder chamber is engaged by the locking lever. The pin is released from the locking lever by manually operating the knob, and the cartridge holder then pivots toward the open position.
In all of the above described mechanisms, the film spool in the film cartridge is engaged at one end by a motorized or manual rewind drive mechanism (for conventional film cartridges) or by a motor driven advance and rewind drive mechanism (for thrust type film cartridges). The other end of the cartridge is typically left free or pressure is applied to the free end (as in the '316 patent described above) and/or laterally to the side of the film cartridge snout or lip by operation of the retention members described above.
In certain of the above-listed patents and in all of the above-listed patent applications, the film cartridge loading chamber or holder is either deployable outward from the camera body, as shown for example in the '316, '547 and '211 patents, or is accessible through an end cover as shown in the '438 patent. Latch mechanisms are required for closing the end covers or securing the deployable chamber in the closed position.
The '316 patent discloses one design of an outward deployable cartridge holder for accepting a film cartridge. In one embodiment, the holder is pivotally supported by a shaft for movement between an outwardly deployed, open position in which the holder projects transversely from the camera body and a closed position in which the cartridge holder stands vertically in the camera body. Upon movement into the closed position and with a film cartridge inserted, the upper end of the cartridge is engaged by a lever to hold the cartridge down. The cartridge holder is normally urged towards the open position. A locking lever operates to retain the cartridge holder in the closed position and is coupled with a knob exposed to the exterior of the camera body. A pin extending from the cartridge holder chamber is engaged by the locking lever. The pin is released from the locking lever by manually operating the knob, and the cartridge holder then pivots toward the open position. Prevention of deploying the cartridge holder with the filmstrip advanced across the exposure gate does not appear to be mentioned. If a filmstrip were extending from the cartridge, it would interfere with the opening motion but only after the deployable film chamber opened partially. The filmstrip could be fogged and damaged in the process.
The '438 patent discloses a stationary film loading chamber with an end opening covered by a loading chamber door that can be opened or closed by manipulation of a slidable door latch so that a thrust film cartridge of the type described above can be loaded or ejected through the open loading chamber door. As indicated in the '438 patent, it is not desirable to allow the loading chamber door to be opened when the filmstrip is extending out of the cartridge door or "light valve", since the filmstrip image frames would be fogged. To prevent this from happening, the loading chamber door latch cannot be released by the user if the film door cannot be closed because the filmstrip is extending through it. This approach depends on contact of the film door with the filmstrip image frame.
The prior art as described above lacks a simple system for detecting the extension of the filmstrip out of the film cartridge and into the filmstrip transport path, particularly for a thrust cartridge, and a deployable film loading chamber that ensures that no damage will be done to the filmstrip or filmstrip image frame.